This invention relates to a treating agent for treating dissolved heavy metals and a method treating dissolved heavy metals with the treating agent.
Such heavy metals as mercury, cadmium, chromium, lead or the like dissolved in water cause a public hazard and research has been made how to remove such dissolved heavy metals. However, according to prior art methods agents for removing the heavy metals and the process of utilizing the treating agents differ variously according to the kinds of the heavy metals to be removed. For example, mercury has been removed by chelate resin absorption method, ferrite method, a method of treating with activated carbon or by a method of coagulating and precipitating with a sulfide; cadmium has been removed by a method of coagulating and precipitating cadmium hydroxide, a chelate resin adsorption method; lead has been removed by a hydroxide coagulation and precipitation method, an ion exchange resin method or an electrolysis isolating method and chromium by a reduction precipitation method, an ion exchange method, a concentrating and recovering method or a foam separating method. Thus the treating agents and methods of treating vary depending upon the kinds of the heavy metals to be removed and the methods require a number of process steps. Especially where a plurality of kinds of heavy metals are contained in an aqueous solution it is necessary to use a number of overlapping process steps. In addition, the prior art methods described above require use of many types of treating agents, thereby increasing the cost of installation and operation. The result of removal of the heavy metals is not always satisfactory and it has been difficult to treat resulting precipitants or absorbed treating agent. These problems become more serious with increase in the concentration of the heavy metals dissolved in the aqueous solution, and the regulations for decreasing the public hazard are becoming more severe, so that to meet these severe regulations expensive installations and high cost operations are necessary, and there has been no efficient method of removing heavy metals contained in a mud or sludge.